Exemplary embodiments of the invention are related to a densifier. More particularly, exemplary embodiments include a system that may be associated with a densifier that facilitates cooling of mechanical components of the densifier and prevents the densified material from plasticizing or melting during the densification process.
The amount of materials ending up in landfills is continuously increasing. As the scarcity of landfill space increases, along with more stringent environmental regulations, there have been increased efforts to reduce the amount of waste produced by individuals, in addition to an increased effort to recycle materials. Many different processes and machines have been developed to facilitate combating this ever-increasing problem.
One of the major contributing materials to landfill overflow are plastics. Additionally, certain types of lightweight plastics, such as, for example, expanded polystyrene (EPS), extruded polystyrene foam, and expanded polypropylene foam are not easily recycled because of their light weight and low scrap value. Many plastics take a very long period of time to biodegrade, if they biodegrade. These types of plastics may also be resistant to photolysis. Furthermore, certain types of lightweight plastics may not only float on water, but may also blow in the wind, causing an abundant amount of litter, especially along shores and waterways.
To combat the littering problem that comes with the use of plastics, different machines and methods of recycling have been developed. This is especially true regarding foamed plastics that typically require an extra step of densifying the foamed plastic. Different machines and methods have been developed to facilitate densification of plastics and other materials that may be recycled. Densification may facilitate the reduction of pentane gas dangers. Also, the densification process may reduce storage requirements and reduce hauling and/or handling costs.
There are currently three different types of densification methods that may be used to densify EPS and other plastics: heat extrusion, ram compaction, and screw compaction using an auger or compactor/compression screw. The known screw densifiers and related methods are less than ideal for densifying or compacting materials. One of the main problems that occur during the densifying process is that the mechanical components used to contact the plastic throughout the screw densification process may heat to undesired levels. This is especially true when known screw densifiers continuously run for extended periods of time. Additionally, another problem that may occur in known densifiers is that the density and/or size of logs or bales produced may fluctuate out of a desired range, producing bales or logs with unwanted characteristics.
Densifiers that use screw compaction have an especially inherent problem with material melt or plasticizing of the material due to the high heat. This occurs when the coefficient of friction between the material and typically the end surface of the compression screw generates high temperatures. Thus, plastics and other materials that have low melt points may be particularly vulnerable to melting during operation of known densifiers. For example, the unwanted temperature of the compression screw may be around 300 degrees Fahrenheit, which may be when the plasticizing of the material occurs. With many materials, it is highly undesirable for the materials to melt during the densification process because the melting may change the composition and/or properties of the material. For example, melting the material may change its functional properties, which may limit its future uses and hence reduce its value. Also, melting the material may change the characteristics of the output (e.g., the density or size of the log) of the densification process, which may reduce the quality of the output and/or impair the operation of the densifier. Also, plasticizing of the material may eliminate or impair the ability of the screw to transmit the force required to move the log of densified material through the compression chamber, ceasing continuous operation until the screw cools and can be cleaned of agglomerated material. Ceasing the continuous operation of the densifier may add extra time and cost to the recycling process.
Given the problems that exist with known screw densifiers, a densifier that incorporates a cooling system that minimizes the heat produced in the shaft and/or flights of the screw while operating the mechanical components of the densifier would be advantageous. Furthermore, providing a cooling system and method of cooling that provides an efficient means to cool the compression screw or other mechanical components is also desirable. Additionally, it is desired that the cooling system and method of cooling may allow the densifier to run on a substantially continuous basis by minimizing or eliminating a buildup of solid material mass caused by melting or plasticizing that could stop or slow down the densifier. Moreover, it is desired that a system is provided that is adapted to monitor when the temperature within the screw densifier reaches an undesired level and adjusts the densifier accordingly. Also, providing a system and method for producing a log or bale that is substantially uniform density and size throughout the length is desired. An exemplary embodiment of a system associated with a densifier that facilitates cooling of mechanical components of the densifier and adjusting the size and density of bales and/or logs produced may satisfy some or all of these needs or preferences.
Although this application may talk about a densifier that employs the method of screw compaction to densify plastics and other materials, the cooling system and method may be used in other applications other than densifying processes. Additionally, although this application may talk about implementing the cooling system with a densifying system that includes a screw compactor, exemplary embodiments of the cooling system may be implemented with any number of densifying, condensing, or other systems that require heat reduction. It should also be noted that the cooling fluid could be replaced by or alternated with a heating fluid for other applications that require heat.
Exemplary embodiments of the system and method may provide a compression screw for advancing plastic material having a hollowed shaft and chambers incorporated in at least one screw flight for the reception of fluid that is temperature controlled to maintain a temperature below that of the plasticizing or melt temperature of the material.
Exemplary embodiments of the system and method may also provide increased volume output of the compression screw through increased speed of the screw, which is facilitated by temperature control of at least the distal end and/or at least one compression flight of the screw.
Further, exemplary embodiments of the system and method may provide increased density of the output log or bale through additional force applied to the screw, which is facilitated by temperature control of at least the distal end and/or at least one the compression flight of the screw.
Exemplary embodiments of the system and method may also provide a novel combination in which a hollowed shaft and/or at least one flight are contained within the compression screw, whereby circulation of temperature controlled fluids may take place in the desired hollowed shaft and/or formed flight chambers.
Exemplary embodiments are directed to a system associated with a densifier adapted to cool mechanical components of the densifier and adjusting the size and density of bales and/or logs produced. Certain embodiments of the system may be used in densifiers of multiple geometries and sizes that are used to densify different materials. Unless expressly set forth, it is not intended to limit the invention to densifying particular materials.
In accordance with exemplary embodiments of the system associated with a densifier and method of use thereof, there is provided an interior hollowed shaft of the screw and a chamber in at least one flight of the screw for temperature control where fluids are circulated so as to maintain the temperature of the screw below the melt or plasticizing temperature of the material. Also, the system elements employed in conjunction with the hollowed shaft of the screw and the chamber in the screw flight(s) may include or be in association with thermo, speed, and/or density controls to control the circulation or lack of circulation of the fluids, temperature of the fluids, and/or volumetric output and density of the material.
In addition to the novel features and advantages mentioned above, other benefits will be readily apparent from the following descriptions of the drawings and exemplary embodiments.